CVE-2026-104140: XSS (CVSS 6.1)

Description

QGIS is a free, open source, cross-platform geographic information system. Prior to 3.44.12 and 4.0.0 through 4.2.3, QGIS Server renders feature data in WFS3 (OGC API Features) HTML responses without HTML escaping. Attacker-controlled feature.properties values from a published writable vector layer reach resources/server/api/ogc/templates/wfs3/getFeatures.html through QgsServerOgcApiHandler::htmlDump and the if_nullptr_null_str callback. A user who opens an items HTML page can execute stored markup or script in the QGIS Server origin, which can expose the viewer's session data or issue authenticated requests with the viewer's privileges. This issue is fixed in version 3.44.12.

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CVSS v3.1 Score

6.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.09%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/qgis/QGIS/commit/1930e81c918818a4f5412219f8f7e470d2709f91 https://github.com/qgis/QGIS/commit/ca76fcac616dbf1c0446514fd6517296eb7c6904 https://github.com/qgis/QGIS/pull/66616 https://github.com/qgis/QGIS/pull/67044 https://github.com/qgis/QGIS/releases/tag/final-3_44_12 https://github.com/qgis/QGIS/security/advisories/GHSA-cr49-pm9v-m788 https://github.com/qgis/QGIS/security/advisories/GHSA-cr49-pm9v-m788

Frequently Asked Questions

What is CVE-2026-104140? +

QGIS is a free, open source, cross-platform geographic information system. Prior to 3.44.12 and 4.0.0 through 4.2.3, QGIS Server renders feature data in WFS3 (OGC API Features) HTML responses without HTML escaping. Attacker-controlled feature.properties values from a published writable vector layer reach resources/server/api/ogc/templates/wfs3/getFeatures.html through QgsServerOgcApiHandler::htmlDump and the if_nullptr_null_str callback. A user who opens an items HTML page can execute stored markup or script in the QGIS Server origin, which can expose the viewer's session data or issue authenticated requests with the viewer's privileges. This issue is fixed in version 3.44.12. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-104140? +

CVE-2026-104140 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-104140? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-104140